Ethylene oxide sterilizing agent



United States Patent 3,359,159 ETHYLENE OXIDE STERILIZING AGENT Robert A. Fulton, Silver Spring, and Edward 0. Haenni, Bethesda, Md., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 22, 1958, Ser. No. 756,739 6 Claims. (Cl. 167-39) 3,359,159 Patented Dec. 19, 1967 Freon 21 (dichlorofluoromethane),

Freon 112 (tetrachlorodifluoroethane),

Freon 113 (trichlorotrifluoroethane),

Freon l 14 (dichlorotetrafluoroethane) Methylene chloride (dichloromethane),

Methyl chloroform (1,1,l-trichloroethane), and Methyl bromide.

Low pres-sure containers are commercially available and are less expensive to manufacture, thus materially reducing the total cost of the finished product.

A preferred formulation comprises a 12% solution of liquified ethylene oxide in a mixture of equal parts of liquified Freon 11 land Freon 12. The latter mixture is commercially available. Parts and percentages referred to are by weight of the components. Thus, such a composition contains 12% by weight of ethylene oxide and ly, this invention relates to gaseous disinfecting and sterilizing agents which are stored as liquids under pressure in containers and which may be released into the atmosphere through a valve in. the container.

It is known that ethylene oxide, which is a gas at room temperature (B.P. 10.7 C.), is an extremely powerful germicide and is effective when released into the atmosphere in a closed room or cabinet to kill bacteria and spores.

It has been proposed to package liquefied ethylene oxide as an 11 to 19% solution in liquefied Freon 12 (dichlorodifiuoromethane) under pressure in a container similar to those commonly in use to disperse insecticide aerosols and to release the desired amount of gas for sterilizing purposes as needed, the Freon 12 serving as a propellant for the ethylene oxide. However, ethylene oxide is an extremely inflammable substance and in concentrations of about 19% in dichlorodifluoromethane or even somewhat lower may produce explosive vapors. In concentrations of 11 or 12% by weight (i.e., 26.5 or 28.5 mole percent, respectively) explosion danger is practically non-existent while the disinfectant properties are retained.

However, since liquefied Freon 12 exerts a pressure of about 85 p.s.i. the preparation must be put up in a high pressure container such as the ICC 9 or ICC 40 to meet Interstate Commerce Commission regulations. Such containers are commercially available for packaging insecticides which are to be used in the form of aerosols, but are relatively high in cost.

It is an object of the present invention to provide an ethylene oxide-propellent solution of effective concentration which will produce a non-explosive vapor and which may be packaged in Interstate Commerce Commission approved low pressure containers. A further object of this invention is to provide a liquefied ethylene oxidepropellent mixture which will have a pressure not exceeding 40 p.s.i. Other objects and advantages will become apparent to those skilled in the art from the following description.

In accordance with the present invention liquified ethylene oxide is dissolved in a propellent which comprises a mixture of Freon 12 and a suppressor for the vapor pressure of Freon 12, such as Freon 11 (trichlorofiuoromethane). These substances are also commercially available under the names Genetron-lZ and Genetron-ll, respectively. Freon 11, having a high boiling point and lower vapor pressure than Freon 12, serves as a suppressor, thus reducing the pressure inside the container. Other suppressors which can be used in place of Freon 11 or in combination therewith are:

44% by weight each of Freon l1 and 12. In terms of mole percentages, these proportions are 28.5%, 33.48%, and 38.02%, respectively. For a composition containing 11% by weight of ethylene oxide and the said Freon mixture containing equal parts of Freon 11 and 12 (i.e.', 44.5% by Weight each of the two Freons), the corresponding mole percentages would be 26.5% ethylene oxide, 34.5% Freon 11, and 39.0% Freon 12.

The invention is further illustrated by the following examples:

Example 1 940 grams of liquified ethylene oxide, which had previously been distilled to purify it, were carefully transferred from a supply cylinder to a weighed evacuated cylinder provided with a valve. The valve was shut after the desired amount of ethylene oxide had been transferred and the supply cylinder disconnected. A second supply cylinder containing a liquified mixture of equal parts of Freon 11 and Freon 12 was then connected to the evacu ated cylinder containing the 940 grams of ethylene oxide and 6896 grams of the Freon mixture were transferred. The evacuated cylinder then contained 7836 grams of a solution of ethylene oxide in the Freon ll-Freon 12 mixture in which the concentration of ethylene oxide was 12% and the two Freons were each present in the amount of 44%. This mixture was non-explosive.

359.2 grams of the above solution (equivalent to 50 ml. ethylene oxide) were transferred to each of a number of commercially available 12 02. low pressure cans. These cans were tin-lined with no exterior enamel, were provided with nylon gaskets, lambs wool filters and had 0.030" orifices.

The pressure within the cans was about 38 p.s.i. thus complying with Interstate Commerce Commission regulations for low pressure containers.

Example 2 The following experiment was carried out to demonstrate the sterilizing power of the 12% ethylene oxide composition described above:

Miscellaneous articles of clothing, including shirts, trousers, underwear, sox, hats, overcoats, and shoes were put into polyethylene bags, each six mils in thickness. Cotton cloth patches carrying the spores of B. subtillus var. niger (B. globigii) were also put into the bags and distributed among the clothing.

A single shot capsule provided with a snap-off top and containing the 12% ethylene oxide solution described in Example 1 was then put into each bag and the bags were sealed. The capsules were opened by breaking off the tops, thus releasing the ethylene oxide-Freon mixture as a gas inside the bags. After 6 to 8 hours the bags were opened and the spore-laden cloth patches were examined and incubated.

It was found that all of the spores had been killed.

We claim:

1. A noninflammable sterilizing agent comprising a mixture of about from 11 to 12% by Weight of ethylene oxide and the balance being a mixture of dichlorodifluoromethane and a member of the group consisting of dichlorofluorornethane, tetrachlorodifluoroethane, trichlorotrifiuoroethane, dichlorotetrofluoroethane, dichloromethane, 1,1,1-trichloroethane, methyl bromide, and mixtures thereof.

2. A sterilant comprising a mixture of ethylene oxide, dichlorodifiuoromethane, and trichloromonofluoromethane in the proportions of 26.5 mole percent ethylene oxide, 39.0 mole percent of dichlorodifluoromethane, and 34.5 mole percent of trichloromonofluoromethane.

3. A sterilant comprising a mixture of ethylene oxide, dichlorodifluoromethane, and trichloromonofluoromethane in the proportions of about 26.5 to 28.5 mole percent of ethylene oxide, 38.02 to 39.0 mole percent of dichlorodifluoromethane, and 33.48 to 34.5 mole percent of trichloromonofluorometane.

4. A noninfiammable sterilizing agent comprising about 12% ethylene oxide, about 44% dichlorodifiuoromethane and about 44% trichlorofluoromethane.

5. A noninfiammable sterilizing agent comprising a liquid mixture of about 12% ethylene oxide, about 44% dichlorodifluoromethane, and about 44% trichlorofluoromethane.

6. An article of manufacture comprising a liquid sterilizing agent composed of about 12% ethylene oxide, about 44% dichlorodifluoromethane, and about 44% trichlorofluoromethane packaged in a container provided with a valve adapted to release said disinfectant as a gaseous mixture into the atmosphere.

References Cited UNITED STATES PATENTS 2,037,439 4/ 1936 Schrader 167-33 2,321,023 6/1943 Goodhue 16739 2,529,092 11/ 1950 Lodes 167-39 2,802,722 8/1957 Elder 167--39 2,891,838 6/1959 Kaye 16739 OTHER REFERENCES ALBERT T. MEY-E-RS, Primary Examiner.

M. O. WOLK, W. B. KNIGHT, J. LEVITI', Examiners.

30 P. CARVELLAS, A. P. FAGELSON, D. R. MAHA- NAND, G. A. MENTIS, Assistant Examiners. 

1. A NONINFLAMMABLE STERLIZING AGENT COMPRISING A MIXTURE OF ABOUT FROM 11 TO 12% BY WEIGHT OF ETHYLENE OXIDE AND THE BALANCE BEING A MIXTURE OF DICHLORODIFLUOROMETHANE AND A MEMBER OF THE GROUP CONSISTING OF DICHLOROFLUOROMETHANE, TETRACHLORODIFLUOROETHANE, TRICHLOROTRIFLUOROETHANE, DICHLOROTETROFLUOROETHANE, DICHLOROMETH-ANE, 1,1 ANE, 1,1,1-TRICHLOROETHANE, METHYL BROMIDE, AND MIXTURES THEREOF. 